Air bag inflation exit gas dispersion features

ABSTRACT

An air bag device that comprises an air bag cushion, a diffuser canister, and a gas generation inflator. The diffuser canister is attached to the air bag cushion and has walls configured to define an interior space therein. The walls of the diffuser canister have an interior surface, an exterior surface, and a wall thickness t. At least one of the walls has an aperture formed therethrough in communication with the interior of the air bag cushion. The gas generation inflator is configured to rapidly create a gas that exists the diffuser canister through the aperture so as to fill the air bag cushion. The aperture is defined by an edge extending between the interior and said exterior surfaces of the wall that is configured to diffuse the gas exiting the diffuser canister through the aperture. The edge of the aperture is configured such that the cross-sectional area of the aperture that is proximate to the exterior surface of the wall is larger than the cross-sectional area of the aperture proximate to the interior surface of wall. The edge includes an angled portion configured such that opposing sides of the aperture have an angle α therebetween in the range of about 20 degrees to about 145 degrees. The aperture has a diameter d 1  proximate to the interior surface of the wall and is configured so that the diameter d 1  and wall thickness t have a ratio d 1  to tin the range of about 0.5 to about 4. An alternate embodiment of the air bag device comprises an aperture defined by an edge that is configured so that the cross-section of aperture is non-smooth and causes turbulence in the gas stream.

BACKGROUND OF THE INVENTION

[0001] 1. The Field of the Invention

[0002] The present invention relates to a safety device usedparticularly in automobiles which, upon the onset of a collision,deploys an inflatable restraint cushion, known as an air bag cushion, toprotect the occupants of the vehicle from the impact of the collision.More particularly, this invention relates to an apparatus for protectingthe inside surface of an air bag cushion from the hot concentrated gasesgenerated during the deployment of the air bag cushion.

[0003] 2. The Relevant Technology

[0004] An air bag assembly typically includes a diffuser canister thatencloses or is attached to a gas generator commonly known as aninflator, at least part of an air bag cushion, and may include a coverwhich conceals the air bag assembly from view. The air bag assembly isoften considered as a module, and the industry is constantly trying toreduce the size of the air bag assembly.

[0005] When the vehicle, usually an automobile, is involved in acollision, a crash signal actuates the gas generation inflator to causethe air bag cushion to deploy. Typically, the actuator triggers achemical or pyrotechnic reaction in the gas generator inflator. Thereaction in gas generation inflator produces an inert gas, usuallynitrogen, which is directed under pressure into the air bag cushion toforce the air bag cushion out of the diffuser canister and into thepassenger compartment of the vehicle. In a pyrotechnic-type gasgeneration inflator, gas is produced by the burning of a gas-generatingmaterial.

[0006] As the air bag cushion is forced out of the diffuser canisterduring deployment, the pressure exerted on the cover causes selectedportions of the cover to separate in a predetermined manner along tearseams to enable the air bag cushion to be directed into the passengercompartment. As the air bag cushion is directed into the passengercompartment, it is inflated by the continued flow of gas produced by thegas generation inflator. Air bag assemblies are typically installed inthe steering column of the vehicle, and another air bag assembly isplaced in the instrument panel or dashboard on the passenger side of thevehicle. An air bag cushion is usually made of a synthetic material thatis substantially impermeable to the flow of gas.

[0007] Initially during the air bag cushion deployment, prior to the airbag cushion rupturing the tear seams of the cover, the gas generationinflator generates a large volume of hot gases under high pressure. Thehot gases exiting the gas generation inflator and diffuser canisterimpact the inside surface of the air bag cushion. This is particularlyproblematic for the portions of the inside surface of the air bagcushion that are proximate to the apertures formed in the diffusercanister through which the gases exit the diffuser canister and gasgeneration inflator and enter the air bag cushion. In most cases, theapertures are smooth and round which causes the gas exiting the diffusercanister to be in a concentrated stream of gas. The concentrated streamof gas exits the diffuser canister so quickly at such a high pressureand with such force that the inside surface of the air bag cushion isdamaged. When the reaction occurring in the gas generation modulecreates hot gases, the concentrated streams of gas scorch the insidesurface of the air bag cushion and may even burn through the air bagcushion. If a more energetic deployment takes place, the hot gasesgenerated by the gas generation inflator can structurally affect the airbag cushion. Designers of the air bag assemblies have been limited inwhat type of reactions can be used to deploy the air bag cushion by thetemperature and/or pressure of the gases exiting the diffuser canisterthat can withstand the air bag cushion.

[0008] Several different types of changes have been made to the air bagassembly to attempt to solve the problems caused by the concentratedstreams of gas damaging the inside surface of the air bag cushion. Oneattempt to reduce the damage to the inside surface of the air bagcushion has been to add extra linings or layers to the air bag cushionto those areas where the concentrated streams of gas come into contactwith the material of the air bag cushion. One type of added layer thathas been incorporated in the air bag cushion is a combined heat andenergy absorbing bag. The liner is in the form of a fiberglass bag, butis not stretchable or a low porosity bag. This inner bag limits thedesign of air bag cushions as well as the size that the module can bereduced to. Adding additional layers or linings to portions of the airbag cushion increases the manufacturing steps, the manufacturing time,and the cost of the air bag cushion itself Additional layers, of evenjust the synthetic material that the air bag cushion is usually made upof, also increases the amount of space that the stored air bag willrequire, and becomes a limiting factor when trying to reduce the size ofthe module.

[0009] Other attempts to protect the inside of the air bag cushion haveincluded attaching some type of a deflector on the diffuser canister ormaking a deflector that is movably positioned between the diffusercanister and the inside surface of the air bag. One deflector consistedof a metal sheet that was formed into an open ended cylinder to act as aheat shield around the diffuser canister. The shield provided protectionto the air bag cushion immediately adjacent to the inflator. Anotherattempt to protect the inside surface of the air bag cushionincorporated a fabric heat shield that was attached to the air bagcushion. When the air bag cushion was deployed, the streams ofconcentrated gases hit the fabric shield instead of the inside of theair bag cushion. Both of these methods, however, required the use ofadditional pieces in the air bag assembly. It was particularlydifficult, when assembling the diffuser canister and the air bag cushionto insure that the fabric shield was in the right position to intersectthe concentrated flow of gases. Both of these deflectors, as well assimilar methods, also limited how small the air bag assembly modulecould be made.

SUMMARY AND OBJECTS OF THE INVENTION

[0010] It is an object of the present invention to protect the insidesurface of the air bag cushion from the concentrated streams of gasesproduced during deployment of the air bag cushion without increasing thethickness of the air bag cushion.

[0011] Another object of the present invention is to protect the insidesurface of the air bag cushion from the concentrated streams of gasesproduced during deployment of the air bag cushion without increasing thenumber of parts in the air bag cushion assembly.

[0012] Another object of the present invention is to protect the insidesurface of the air bag cushion from very hot gases exiting the diffusercanister.

[0013] A further object of the present invention is to disperse thestreams of gas exiting the diffuser canister to reduce or eliminate anydamage the gases cause to the inside surface of the air bag cushion.

[0014] A further object of the present invention is to cause turbulencein the streams of gas exiting the diffuser canister thereby reducing oreliminating the damage the gases cause to the inside surface of the airbag cushion.

[0015] Additional objects and advantages of the invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims.

[0016] To achieve the foregoing objects, and in accordance with theinvention as embodied and broadly described herein, an air bag device isprovided that comprises an air bag cushion, a diffuser canister, and agas generation inflator. The diffuser canister is attached to the gasinlet opening of the air bag cushion and has walls configured to definean interior space therein. The walls of the diffuser canister have aninterior surface, an exterior surface, and a width of thickness t. Atleast one of the walls has an aperture formed therethrough incommunication with the interior of the air bag cushion. The aperture isdefined by an edge extending between the interior and said exteriorsurfaces of the wall. The gas generation inflator is configured torapidly create a gas that exits the diffuser canister through theaperture so as to fill the air bag cushion. The air bag device alsocomprises a dispersing means for diffusing the gas exiting the diffusercanister through the aperture. The dispersing means comprises the edgethat defines the perimeter of the aperture and is configured such thatthe cross-sectional area of the aperture that is proximate to theexterior surface of the wall is larger than the cross-sectional area ofthe aperture proximate to the interior surface of the wall. The edge ofthe aperture comprises an angled portion. The angled portion of the edgeon opposing sides of the aperture has an angle α therebetween of about20 degrees to about 145 degrees. The aperture has a diameter d₁proximate to the interior surface of the wall and the diameter d₁compared to the wall thickness t has a ratio of about 0.5 to about 4.

[0017] An alternate embodiment of the air bag device comprises an airbag cushion, a diffuser canister, and a gas generation inflator. Thediffuser canister has a plurality of walls configured to define aninterior space therein. Each of the walls has an interior surface and anexterior surface. One of the walls has at least one aperture formedtherethrough in communication with the interior of said air bag cushion.This embodiment of an air bag device includes means for causingturbulence in the gas exiting the diffuser canister through the aperturethat comprises an edge defining the periphery of the aperture. The edgehas an angled portion that is configured such that the cross-section ofaperture is non-smooth, and consequently, causes turbulence in said gas.

[0018] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order that the manner in which the above-recited and otheradvantages and objects of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to a specific embodiment thereof which is illustrated in theappended drawings. Understanding that these drawings depict only atypical embodiment of the invention and are not therefore to beconsidered to be limiting of its scope, the invention will be describedand explained with additional specificity and detail through the use ofthe accompanying drawings in which:

[0020]FIG. 1 is a partial cross-sectional elevation view of the air bagassembly during the deployment of the air bag cushion;

[0021]FIG. 2 is a partial cross-sectional elevation view of thestructure of FIG. 1 with an air bag cushion attached thereto;

[0022]FIG. 3 is a partial cross-sectional view of the structure of FIG.1 taken along the section line 3-3 therein;

[0023]FIG. 4 is another embodiment of the apertures formed in the airbag assembly during the deployment of the air bag cushion;

[0024]FIG. 5 is a partial cross-sectional elevation view of thestructure of FIG. 4 with an air bag cushion attached thereto;

[0025]FIG. 6 is another embodiment of the apertures formed in the airbag assembly during the deployment of the air bag cushion;

[0026]FIG. 7 is a partial cross-sectional elevation view of thestructure of FIG. 6 with an air bag cushion attached thereto;

[0027]FIG. 8 is another embodiment of the apertures formed in the airbag assembly during the deployment of the air bag cushion; and

[0028]FIG. 9 is a partial cross-sectional elevation view of thestructure of FIG. 8 with an air bag cushion attached thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention relates to an air bag assembly that isconfigured to cause the gases that are rapidly created in a gasgeneration inflator to flow out a diffuser canister and into an air bagcushion while simultaneously diffusing the gas stream and/or causingturbulence in the gas stream to reduce the damage that a concentratedstream of gas has on the inside surface of the air bag cushion. Oneembodiment of an air bag assembly is shown generally in FIGS. 1 and 2 at10, and includes a gas generation inflator 12, a diffuser canister 14,and an air bag cushion 16.

[0030] Gas generation inflator 12 is depicted in FIGS. 1 and 2 as beingsubstantially square-shaped. Gas generation inflator 12 has a flange 22that is configured to cooperate with diffuser canister 14. Flange 22 mayhave various other configurations as long as it cooperates with diffusercanister 14. Gas generation inflator 12 is configured to securelycontain reactants therein that upon the happening of a crash will beactuated to trigger a reaction, including a chemical reaction or apyrotechnic reaction, which rapidly creates enough gas to inflate airbag cushion 16. The specifics of the reaction is beyond the scope ofthis patent and are known by those skilled in the art.

[0031] Diffuser canister 14 is depicted as having a substantially roundconfiguration. As illustrated in FIG. 2, diffuser canister 14 includes aside wall 18 and a top wall 20. Top wall 20 defines a closed end ofdiffuser canister 14 while the remote end of side wall 18 defines anopen end of diffuser canister 14 which cooperates with flange 22 of gasgeneration inflator 12. Side wall 18 and top wall 20 of diffusercanister 14 together with gas generation inflator 12 define an interiorspace 24. Side wall 18 may have various other configurations as long asthe remote end of side wall 18 cooperates with flange 22 on gasgeneration inflator 12.

[0032] It can be appreciated that various other configurations andshapes of gas generation inflator 12 and diffuser canister 14 areequally effective at carrying out the intended function thereof. By wayof example and not limitation, gas generation inflator 12 may have othershapes including rectangled, oval, or round. Similarly, diffusercanister 14 may have other configurations such as oval, octagonal, orelliptical. The important feature is that gas generation inflator 12 anddiffuser canister 14 are configured to cooperate and define an interiorspace 24 in which a reaction which rapidly creates the gas takes placeupon receiving the actuating signal.

[0033] Side wall 18 of diffuser canister 14 has apertures 26 formedtherethrough as depicted in FIGS. 1 and 2. Apertures 26 aresubstantially equally spaced around side wall 18. It is preferred thatdiffuser canister 14 have between 6 to 60 apertures formed therein. Oneembodiment of diffuser canister 14 has twelve (12) apertures 26 formedthrough side wall 18. It can be appreciated by those skilled in the artthat various other numbers and arrangements of apertures 26 are equallyeffective in carrying out the intended function thereof. Apertures 26will be discussed in more detail below.

[0034] As previously mentioned, air bag assembly 10 includes air bagcushion 16. Air bag cushion 16 has a gas inlet opening 28, oftenreferred to as a throat, and a closed end (not shown) that upondeployment of air bag cushion 16 will protect a person in the vehiclefrom impact. Gas inlet opening 28 of air bag cushion 16 is attached toflange 22 of gas generation inflator 12 by an attaching mechanism, suchas a collar assembly 30 illustrated in FIG. 2. Collar assembly 30 holdsgas inlet opening 28 of air bag cushion 16 in such a way that air bagcushion 16 is substantially sealed and the gas rapidly flowing into airbag cushion 16 is contained therein.

[0035] One embodiment of collar assembly 30 comprises a housing 32 and aretaining ring 34. Housing 32 may be mounted on flange 22 of gasgeneration inflator 12 by conventional methods including welding orbolting. Gas inlet opening 28 of air bag cushion 16 is positioned onhousing 32 and retaining ring 34 is attached to housing 32 so as to holdair bag cushion 16 between housing 32 and retaining ring 34. One waythat retaining ring 34 is attached to housing 32 is by bolts. It can beappreciated, however, that various other methods can be used includingscrews and brackets.

[0036] Various other attaching mechanisms or configurations of collarassembly 30 are equally effective in carrying out the intended functionof attaching gas inlet opening 28 of air bag cushion 16 to gasgeneration inflator 12. Although, air bag assembly 10 has been depictedas having air bag cushion 16 attached to flange 22 of gas generationinflator 12, it is contemplated that air bag cushion 16 could be mountedto a flange or collar formed on diffuser canister 14. The limitationwith this alternate configuration is that apertures 26 must beunobstructed.

[0037] Prior to the occurrence of the gas producing reaction, it ispreferred that apertures 26 be covered with a relatively thin covering,such as a foil (not shown). One type of foil that can be used isaluminum foil. The foil prevents moisture from entering interior space24 and potentially interfering with the gas producing reaction thattakes place in gas generation inflator 12. Upon receiving an actuationsignal, typically in the form of an electric actuation signal from acrash sensor (not shown), the gas producing reaction is triggered in gasgeneration inflator 12. The foil covering aperture 26 also initiallyallows the pressure to build in interior space 24 after the reaction hasbeen actuated and the gas is being created. Pressure within interiorspace 24 builds until it reaches a point that the gas being rapidlycreated in the gas generation inflator 12 bursts through the foilcovering apertures 26 and escapes out diffuser canister 14 throughapertures 26 into air bag cushion 16. The initial pressure build up ininterior space 24 caused by the foil has been shown to improve theeffectiveness and completeness of the gas producing reaction,particularly pyrotechnic reactions, occurring in gas generation inflator12.

[0038] As previously discussed, gas generation inflator 12 rapidlyproduces gases that after breaking though the foil escape from interiorspace 24 through apertures 26 into air bag cushion 16. Typically, thegases produced by the pyrotechnic reaction and exiting diffuser canister14 are concentrated, are hot, and are under pressure. As a result, thesegases are potentially harmful to inside surface 36 of air bag cushion 16and can damage the air bag cushion by scorching, melting, or evenburning through air bag cushion 16. The design of apertures 26 plays akey role in substantially reducing and even totally preventing damage orother harmful effects from the hot gases to inside surface 36 of air bagcushion 16.

[0039] According to another aspect of the present invention, air bagassembly 10 comprises dispersing means for diffusing the gas exitingdiffuser canister 14 through apertures 26. The structure performing thefunction of such a dispersing means for diffusing the gases exitingdiffuser canister 14 comprises an edge 42 that extends between aninterior surface 38 of side wall 18 and an exterior surface 40 of sidewall 18 as shown in FIG. 3. It is intended that “edge 42” is notnecessarily one continuous surface. Instead, the term “edge 42” isintended to be broad enough to encompass the entire peripheral boundaryof side wall 18 that defines aperture 26.

[0040] Edge 42 is at least partially comprised by an angled portion,such as angled portion 44 shown in FIG. 3. While the embodimentillustrated in FIGS. 1-3 has been countersunk, it is intended thataperture 26 with angled portion 44 can be formed by other conventionalmanufacturing methods. Aperture 26 as depicted in FIG. 3, actuallycomprises angled portion 44 that is at an angle relative to exteriorsurface 40 of side wall 18 and an optional portion 46 that issubstantially parallel with the gas flow through aperture 26. Aperture26 is equally effective without portion 46. Conventional manufacturingprocesses, such as by way of example and not limitation stamping andcoining, usually result in a portion of edge 42 proximate to interiorsurface 38 being having a slightly different contour than angled portion44. Regardless of the specific configuration of edge 42, aperture 26will usually have a diameter d₁ proximate to interior surface 38 of sidewall 18 that is smaller than diameter D₂ proximate to exterior surface40.

[0041] Angled portion 44 is more significant than portion 46 indiffusing the gas stream. Angled portion 44 has an angled relationshipequal to the angle β to the central axis a of aperture 26. An angle αextends between opposing angled portions-44 of aperture 26 shown in FIG.3. Angle α may have a range of about 20 degrees to about 145 degrees. Amore preferred range for the angle α is about 110 degrees to about 130degrees. Most preferably angle α is 118 degrees. FIG. 3 depicts theangle α as being symmetric about the central axis a of aperture 26.There is, however, no requirement that the angle α be symmetric to thecentral axis a of aperture 26.

[0042] The reaction occurring in gas generation module 12 creates gas soquickly that once the foil over aperture 26 is broken the gas has a veryhigh velocity and pressure. Diameter d₁ proximate to interior surface 38limits the flow rate of the gases out of aperture 26. The configurationof edge 42, particularly the angle α of angled portion 44, allows thegas flowing though diameter d₁ toward diameter D₂ to expand. As the gasenters aperture 26 through diameter d₁ with a pressure p₁. velocity v₁,and temperature T₁, angled portion 44 allows the gas to expand and exitaperture through diameter D₂ with pressure P₂, velocity V₂ andtemperature T₂. Consequently, the temperature and pressure of the gasexiting diameter D₂ are reduced as compared to the pressure Pi andtemperature T₁.

[0043] There are some limitations of the effectiveness of the angle a ofangled portion 44. The ratio of the diameter d₁ of aperture 26 to thewall thickness t of side wall 18 is a limiting factor, because at somepoint the wall will be so thin that the angle α has minimal effect.However, because the gases exit diffuser canister 14 at such a highvelocity and pressure when air bag cushion 16 is deployed the wallthickness t of side wall 18 can be very thin. The wall thickness t ofside wall 18 may have a range of about 0.030 inches to about 0.3 inches.Preferably side wall 18 has a thickness of about 0.060 inches to about0.130 inches. Diameter d₁ may have a range of about 0.5 inches to about0.05 inches. It is preferred that diameter d₁ have a range of about0.100 inches to about 0.160 inches. More important is the ratio ofdiameter d₁ to wall thickness t of side wall 18. The ratio of diameterd₁ to wall thickness t can be in the range from about 0.5 to about 4.The preferred diameter d₁ to wall thickness t ratio is about 0.9 toabout 2.3.

[0044] As previously discussed, diffuser canister 14 has apertures 26formed though side wall 18. Apertures 26 may or may not be evenly spacearound the periphery of diffuser canister 14. The spacing requirement ofapertures 26 is dependent on the size and configuration of apertures 26.Apertures 26 may all be the same size or may be of varying sizesdepending on the configuration of edge 42.

[0045] FIGS. 4-9 illustrate other embodiments of apertures formedthrough side wall 18 of diffuser canister 14. The majority of thefeatures previously discussed relative to air bag assembly 10 apply tothe other embodiments of the air bag assemblies. The features that arenot affected are identified with the same reference numbers as used inFIGS. 1-3. Only those features that have changed will be described indetail.

[0046]FIGS. 4 and 5 illustrate another embodiment of apertures 60 formedthrough side wall 18 of diffuser canister 14. According to anotheraspect of the present invention, air bag assembly 10 comprises means forcausing turbulence in the gas exiting diffuser canister 14 throughapertures 60. Structure performing the function of such a dispersingmeans for diffusing the gases exiting diffuser canister 14 comprises anedge 62.

[0047] Edge 62 comprises angled portion 44 with an angle α betweenopposing sides of aperture 60. Aperture 60 with edge 62 is angled suchthat the gas stream flowing out of aperture 60 is directed towardanother aperture 60 to intersect the gas stream flowing from a similarlydirected aperture 60. The intersection or impinging of the two streamsof gas disrupts the gas stream and causes turbulence in the flow as willbe discussed below. FIG. 5 illustrates several variations in thearrangement of apertures 60. Edge 62 with angled portion 44 alsodiffuses the gas exiting apertures 60.

[0048] Unlike apertures 26 illustrated in FIG. 2, apertures 60 are notevenly spaced around the periphery of diffuser canister 14. Instead,apertures 60 are arranged so that the those apertures 60 whose gasstreams are intended to intersect are somewhat closer together. Thedistance between apertures 60, as well as the angle α and β of angledportion 44 of edge 62, determines where the streams of gas willintersect. It is to be understood that it is not necessary that aperture60 be unevenly spaced around the perimeter of diffuser canister 14.Evenly spacing apertures 60 carries out the intended function thereofequally effectively. Instead of adjusting the spacing, the angles α andβ of angled portion 44 of edge 62 can be changed to cause the gasstreams to cross. In addition, it is not necessary that apertures 60 bearranged in pairs, instead apertures 60 could be arranged in threes, orfours or other arrangements where the streams of gas can be redirectedcausing them to intersect and create turbulence in the gas flow.

[0049]FIGS. 4 and 5 illustrate one possible arrangement where apertures60 are arranged in pairs so that the gas stream flowing out eachaperture 60 quickly impinges upon the gas stream flowing out anotheraperture 60. FIG. 5 also illustrates two variations in the configurationof aperture 60 itself. Apertures 60 on the left hand side of FIG. 5 aredirected such that the flow is upwardly away from retaining ring 34. Incontrast, apertures 60 illustrated on the right hand side of FIG. 5 aredirected such that the gas flowing from apertures 60 is directeddownward towards retaining ring 34. It is contemplated that apertures 60may be arranged in an alternating manner as illustrated or in any othercombination thereof. It is also contemplated that apertures 60 coulddirect the gas flow outward substantially perpendicular to exteriorsurface 40 of side wall 8 instead of upward or downward as illustratedin FIG. 5.

[0050] As previously mentioned, the intersection of the streams of gasdisrupts the gas flowing out aperture 60 toward inside surface 36 of airbag cushion 16 and causes turbulence in the gas flow. In addition,angled portion 44 disperses the gas stream. FIGS. 4 and 5 also depictapertures 60 as being countersunk similar to apertures 26 illustrated inFIGS. 1-3. As shown in FIG. 4, edge 62 comprises angled portion 44 whichin this embodiment is symmetric about the center axis a of aperture 60.Therefore, angle β is equal to one half of the angle α.

[0051] Although, both FIGS. 4 and 5 depict apertures 60 as beingcountersunk, it is contemplated that apertures 60 could not have acountersink and that edges 62 that define apertures 60 may be paralleland entirely comprised by angled portion 44. In this embodiment, thediameter of apertures 60 would be constant. Apertures 60 would stilldirect the flow of gas out aperture 60 in such a direction as to impingeupon the flow of gas out an adjacent aperture 60 to cause turbulence ingas flowing out the apertures.

[0052] The advantage of using the countersink illustrated in FIGS. 4 and5 is that the gas stream has been widened. Apertures 60 are capable ofboth causing turbulence and diffusing the gas flow. The turbulencecaused by the intersecting streams of gas further disperses the gas andfurther reduces the pressure, velocity, and temperature of the gasstream. In some cases, it may not be necessary to both countersink andredirect the gas flow to intersect with other streams of gas. Forexample, depending on the type of reaction, and the type of material airbag cushion 16 is made of, it may be sufficient just to redirect the gasstreams to intersect thereby disrupting the gas streams and causingturbulence. Widening and dispersing of the gas stream by thecountersinking may not be needed. It is contemplated that anycombination may be used.

[0053] It should be noted that as depicted in FIGS. 4 and 5, diameter d₁adjacent to interior wall 38 has the same central axis a as the angledportion. This is not required. Instead, a two step operation could havebeen used to form diameter d₁ with a central axis a that isperpendicular to the exterior surface 40 of side wall 18, as shown inFIG. 3. A second operation could then be performed. In thisconfiguration angle α would not be symmetric about the central axis a ofaperture 60. In other words, the angle β would not be one half of theangle α. Either configuration of aperture is effective in carrying outthe intended function thereof.

[0054]FIGS. 6 and 7 depict another embodiment of apertures 70 formedthrough side wall 18 diffuser canister 14. As depicted, apertures 70 are“star-shaped”. Unlike, apertures 26 and 60 illustrated in FIGS. 1-5,apertures 70 are defined by an edge 72 that is substantiallyperpendicular to the exterior surface 40. The non-smooth configurationof apertures 70 creates turbulence in the stream of gas that is flowingout of apertures 70 which reduces the concentration of the gas and helpsreduce the temperature of the stream of gas flowing out of apertures 70.Although apertures 70 are depicted as star-shaped, apertures 70 can havevarious other shapes as long as the periphery defined by edge 72 isnon-smooth and irregular. By way of example and not limitation, othernon-smooth shapes include any scalloped-shaped opening.

[0055] It can be appreciated by those skilled in the art thatconventional manufacturing processes, such as by way of example and notlimitation, stamping and coining, may result in a portion of edge 72proximate to interior surface 38 of side wall 18 having a slightlydifferent contour than the rest of edge 72. This might be caused bytearing or deformation of side wall 18 during the manufacturing process.

[0056]FIGS. 8 and 9 illustrate another embodiment of apertures 80 formedin side wall 18 of diffuser canister. As shown in the figures, apertures80 are countersunk similar to apertures 26 illustrated in FIGS. 1-3.Apertures 80 are, however, star-shaped which results in apertures 80having a non-smooth and irregular edge 82. Edge 82 comprises angledportion 44 which causes the gas flowing out aperture 80 to diffuse. As aresult, in addition to the turbulence that is caused by the irregularityof edge 82 that defines aperture 80, angled portion 44 diffuses the gas.

[0057] Although FIGS. 1-5 and 7-8 depict the apertures having at least asmall portion 46 of edge 42, 62, or 82 proximate to interior surface 38of side wall 18 being at a different angle than angled portion 44 of theedge, it is not necessary. Angled portion 44 may instead extendsubstantially the entire length of the edge.

[0058] Tests were conducted with the countersunk apertures 26,illustrated in FIGS. 1-3 having various diameters. In addition, variousdiameters d₁ to wall thickness t ratios were studied in the tests todetermine the effectiveness the various configurations.

Example 1

[0059] TABLE 1 Equipment Specifications Air bag cushion 315 denier,uncoated material Gas Generation Inflator MDN-2, Type 6 from AO# G30084(85 grams of generant) 12 apertures (total) 6 apertures with d₁ = .125inches 6 apertures with d₁ = .156 inches Thickness t of side wall .130inches Angle α 118° Thickness of flat portion .020 inches d₁/t Ratio .961.2

[0060] Discussion and Conclusion

[0061] A ratio of diameter d₁ to wall thickness t of 0.96 and 1.2 wasused in this test. Adding a countersink to the apertures helped todisperse the gas stream from each aperture. Diffusing the gas reducedthe concentration of the stream of gas and helped reduce the temperatureand the pressure of the gas impacting upon the inside surface of the airbag cushion. Approximately a 50% reduction in the number of burnedthrough locations in the throat or gas inlet opening of the air bagcushion were observed.

Example 2

[0062] TABLE 2 Equipment Specifications Air bag cushion 420 denier,fully silicone coated material Gas Generation Inflator MDN-2, Type 4 and6 from BS# GY8576 (90 and 85 grams of generant) 12 apertures (total) 6apertures with d₁ = .125 inches 6 apertures with d₁ = .156 inchesThickness t of side wall .130 inches Angle α 118° Thickness of flatportion .020 inches d₁/t Ratio .96 1.2

[0063] Discussion and Conclusion

[0064] A ratio of diameter d₁ to wall thickness t of 0.96 and 1.2 wasused in this test. Adding the countersink to the apertures helped todisperse the gas stream from each aperture. Diffusing the gas reducedthe concentration of the stream of gas and helped to reduce thetemperature and the pressure of the gas impacting upon the insidesurface of the air bag cushion. Approximately a 50% reduction in thenumber of burned through location in the throat or gas inlet opening ofthe air bag cushion proximate to the retaining ring were observed.

Example 3

[0065] TABLE 3 Equipment Specifications Air bag cushion 210 denier,light silicone coated material Gas Generation Inflator MDN-7, from BS#G49151 (37 grams of generant) 12 apertures (total) 4 apertures with d₁ =.100 inches 4 apertures with d₁ = .1285 inches 4 apertures with d₁ =.136 inches Thickness t of side wall .060 inches Angle α 118° Thicknessof flat portion .012 inches d₁/t Ratio 1.67 2.14 2.27

[0066] TABLE 4 Equipment Specifications Air bag cushion 210 denier,light silicone coated material Gas Generation Inflator MDN-7, from BS#G49151 (37 grams of generant) 12 apertures (total) 4 apertures with d₁ =.100 inches 4 apertures with d₁ = .1285 inches 4 apertures with d₁ =.136 inches Thickness t of side wall .060 inches Thickness of flatportion .060 inches d₁/t Ratio 1.67 2.14 2.27

[0067] Discussion and Conclusion

[0068] Table 3 depicts the equipment and specifications used inExperiment 3. Table 4 depicts the standards used for a baselinecomparison. A ratio of diameter d₁ to wall thickness t of 1.67, 2.14,and 2.27 were used in this test. Adding the countersink to the apertureshelped to disperse the gas stream from each aperture. Diffusing the gasreduced the concentration of the stream and helped to reduce thetemperature and the pressure of the gas impacting upon the insidesurface of the air bag cushion. In this experiment, the width of theflat portion proximate to the diameter d₁ was reduced in comparison thethat in Experiment 1 and 2. In addition, in this experiment there werethree sizes of apertures instead of only two sizes.

[0069] A baseline run resulted in two (2) locations of burn through ofthe air bag cushion. In contrast, the configuration used in theexperimental run of Experiment 3 resulted in no cushion burn through.The baseline run indicated that changing the size of the apertures andthe numbers of the variously sized apertures as compared to Experiments1 and 2 did not make a significant improvement. The addition of thecountersink that resulted in the edge that defined the apertures havingin an angled portion appears to be significant.

[0070] Diffusing and/or causing turbulence to the streams of gas exitingdiffuser canister 14 reduces the concentration of the gas flow. Thetemperature and pressure is also decreased. Together these changes inthe gas flow reduces and even eliminates any harmful effect the gas flowhas on the air bag cushions. Designers of gas bag assemblies cancontinue to attempt to minimize the size of the module as well as usehotter and more energetic reactions in gas generation inflator 12.

[0071] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. An air bag device comprising: (a) an air bag cushion; (b)a diffuser canister attached to said air bag cushion, said diffusercanister having at least one aperture formed therein in communicationwith the interior of said air bag cushion; (c) a gas generation inflatorconfigured to rapidly create a gas within said diffuser canister, saidgas existing said diffuser canister through said aperture so as to fillsaid air bag cushion; and (d) dispersing means for diffusing said gasexiting said diffuser canister through said aperture.
 2. An air bagdevice as recited in claim 1 , wherein said dispersing means comprisesan edge defining said aperture, said edge being configured such that thecross-sectional area of said aperture increases as said gas exits saiddiffuser canister so as to diffuse said gas exiting said diffusercanister through said aperture.
 3. An air bag device as recited in claim2 , wherein said edge defining said aperture comprises an angledportion, said angled portion being at non-perpendicular to said diffusercanister.
 4. An air bag device as recited in claim 3 , wherein saidangled portion of said edge on opposing sides of said aperture has anangle α in the range of about 20 degrees to about 145 degrees.
 5. An airbag device comprising: (a) an air bag cushion having a gas inletopening; (b) a diffuser canister attached to said gas inlet opening ofsaid air bag cushions, said diffuser canister having a plurality ofwalls configured to define an interior space therein, each of saidplurality of walls having an interior surface, an exterior surface, anda wall thickness t, one of said plurality of walls having an apertureformed therethrough in communication with the interior of said air bagcushion, said aperture being defined by an edge extending between saidinterior surface and said exterior surface of said wall; (c) a gasgeneration inflator configured to rapidly create a gas within saiddiffuser canister, said gas exiting said diffuser canister through saidaperture so as to fill said air bag cushion; and (d) dispersing meansfor diffusing said gas exiting said diffuser canister through saidaperture, said dispersing means comprising an edge defining theperimeter of said aperture, said edge being configured such that thediameter of said aperture proximate to said exterior surface of saidwall is larger than the diameter d₁ of said aperture proximate to saidinterior surface of said wall.
 6. An air bag device as recited in claim5 , wherein said edge defining said aperture comprises an angledportion, said angled portion on opposing sides of said aperture havingan angle α therebetween in the range of about 20 degrees to about 145degrees.
 7. An air bag device as recited in claim 6 , wherein said angleα of said angled portions of said edge on opposing sides of saidaperture having a range of about 110 degrees to about 130 degrees.
 8. Anair bag device as recited in claim 5 , wherein diameter d₁ of saidaperture and said wall thickness t having a ratio of diameter d₁ to wallthickness tin the range of about 0.5 to about 4.0.
 9. An air bag deviceas recited in claim 8 , wherein said ratio of diameter d₁ to wallthickness t is about 0.9 to about 2.3.
 10. An air bag device comprising:(a) an air bag cushion having a gas inlet opening; (b) a diffuser adiffuser canister attached to said gas inlet opening of said air bagcushion, said diffuser canister having a plurality of walls configuredto define an interior space therein, each of said plurality of wallshaving an interior surface, an exterior surface, and a wall thickness t;(c) a gas generation inflator disposed in said interior space-of saiddiffuser canister, said gas generation inflator being configured torapidly create a gas within said diffuser canister, said gas existingsaid diffuser canister through said aperture so as to fill said air bagcushion; and (d) an aperture formed through one of said plurality ofwalls, said aperture being in communication with the interior of saidair bag cushion, said aperture being defined by an edge extendingbetween said interior surface and said exterior surface of said wall,said diameter d₁ of said aperture compared to said wall thickness thaving a ratio of about 0.5 to about
 4. 11. An air bag device as recitedin claim 10 , wherein said edge comprises an angled portion, said angledportion on opposing sides of said aperture having an angle αtherebetween in the range of about 20 degrees to about 145 degrees. 12.An air bag device as recited in claim 11 , wherein said angle α of saidangled portions of said edge on opposing sides of said aperture having arange of about 110 degrees to about 130 degrees.
 13. An air bag deviceas recited in claim 10 , wherein said diameter d₁ has a range from about0.5 inches to about 0.05 inches.
 14. An air bag device comprising: (a)an air bag cushion; (b) a diffuser canister attached to said air bagcushion, said diffuser canister having a plurality of walls configuredto define an interior space therein, each of said plurality of wallshaving an interior surface and an exterior surface, one of saidplurality of walls having at least one aperture formed therethrough incommunication with the interior of said air bag cushion; (c) a gasgeneration inflator configured to rapidly create a gas within saiddiffuser canister, said gas existing said diffuser canister through saidaperture so as to fill said air bag cushion; and (d) means for causingturbulence in said gas exiting said diffuser canister through saidaperture.
 15. An air bag device as recited in claim 14 , wherein saidmeans for causing turbulence in said gas exiting said diffuser canistercomprises an edge defining said of aperture.
 16. An air bag device asrecited in claim 15 , wherein said edge comprises an angled portionconfigured to cause said gas exiting from a first aperture to intersectthe flow of gas exiting a second aperture such that turbulence iscreated in said gas flowing from said apertures.
 17. An air bag deviceas recited in claim 15 , wherein said edge defining the periphery ofsaid aperture is configured such that the cross-section of saidapertures is non-smooth.
 18. An air bag device as recited in claim 17 ,wherein said non-smooth cross-section defined by said edge of saidaperture is star-shaped.
 19. An air bag device as recited in claim 17 ,wherein said edge of said aperture is configured such that thecross-sectional area said aperture increases as said gas exits saiddiffuser canister so as to diffuse said gas exiting said diffusercanister through said apertures in addition to causing turbulence. 20.An air bag device comprising: (a) an air bag cushion having a gas inletopening; (b) a diffuser canister attached to said gas inlet opening ofsaid air bag cushion, said diffuser canister having a plurality of wallsconfigured to define an interior space therein, each of said pluralityof walls having an interior surface and an exterior surface; (c) a gasgeneration inflator configured to rapidly create a gas within saiddiffuser canister, said gas existing said diffuser canister through saidaperture so as to fill said air bag cushion; and (d) an aperture formedthrough one of said plurality of wails, said aperture being incommunication with the interior of said air bag cushion, said aperturehaving a non-smooth cross section configured to cause turbulence in saidgas exiting said diffuser canister through said aperture.
 21. An air bagdevice as recited in claim 20 , wherein said aperture is defined by anedge extending between the interior surface and the exterior surface ofsaid wall, said edge comprising an angled portion configured such thatthe cross-sectional area of each of said apertures increases as said gasexits said diffuser canister so as to diffuse said gas exiting saiddiffuser canister through said plurality of apertures in addition tocausing turbulence.